Requires

Soul Echo must be on the battlefield. Soul Conduit must be on the battlefield. Cavern Harpy must be on the battlefield. Mana needed:

Steps

1. Activate Cavern Harpy by paying 1 life.
2. Repeat step 1 until you have zero life.
3. Resolve the last Cavern Harpy trigger, returning it to your hand.
4. The remaining Cavern Harpy triggers fizzle.
5. Activate Soul Conduit by paying and tapping it, exchanging your life total with an opponent's.
6. The opponent loses the game due to having zero life.
7. You may repeat this on each of your turns.

Results